CHAP. IV.] 



THE SKELETON OF THE LIMB& 



95 



round by and with the radius in that motion of the arm and band 

 which is called pronation and supination movements which will be 

 explained when the articulations and ligaments of the pectoral limb 



Fig. 56. THE RIGHT ULNA. 



A. External aspect. 



B. Internal aspect. 



C. Surface of sigmoid fossa, 

 c. Coronoid process. 



gs. Greater sigmoid cavity. 



7s. Lesser sigmoid cavity, 

 o. Olecranon. 

 .r. Surface for radius. 

 s. Styloid process. 



are described. The outer lower end of the radius also presents, in- 

 ternally, a small articular surface for the ulna (it). 



5. The ULNA, or post- axial bone of the forearm, is longer than 

 the humerus, and considerably longer than the radius. While the 

 latter bone is broader below than above, the reverse condition obtains 

 in the ulna. The shaft is flattened both in front and behind, with a 



